1. Field of the Invention
The present invention relates to an information processing apparatus, method, and program, and more particularly to an information processing apparatus, method, and program for enabling a broadcast receiver for receiving broadcast signals to properly receive broadcast signals transmitted with strong radio waves and to have an increased capability for receiving broadcast signals transmitted with weak radio waves.
2. Description of the Related Art
For increasing the reception sensitivity of a broadcast receiver as a capability for receiving weak broadcast signals transmitted with weak radio waves, it is known in the art that it is effective to reduce the NF (Noise Figure) of the broadcast receiver.
According to one approach to reduce the NF of a broadcast receiver, an LNA (Low Noise Amplifier) is connected to the front stage of a tuner incorporated in the broadcast receiver.
There are small-size broadcast receivers such as portable terminals having a function to receive broadcast signals such as television broadcasts known as so-called one-segment broadcasts. Such small-size broadcast receivers are highly limited as to the scale of circuits which can be incorporated therein and the overall receiver size. An LNA with a fixed gain is employed in those small-size broadcast receivers.
FIG. 1 of the accompanying drawings shows a broadcast receiver having an LNA in the related art.
As shown in FIG. 1, the broadcast receiver, generally denoted by 11, includes an input terminal 31, a constant-voltage source 32, an LNA 33, and a tuner 34.
The input terminal 31 is supplied with a broadcast signal (also referred to as RF (Radio Frequency) signal) of a television broadcast from an antenna, not shown. The RF signal supplied to the input terminal 31 is supplied to the LNA 33.
The constant-voltage source 32 includes a battery, for example, and has a negative terminal connected to ground and a positive terminal to a power supply terminal 35 of the LNA 33. The constant-voltage source 32 outputs a constant voltage E that is applied as a power supply voltage to the power supply terminal 35 of the LNA 33.
The LNA 33 includes an amplifying circuit having a single transistor, for example. The LNA 33 amplifies the RF signal (broadcast signal) supplied from the input terminal 31 and supplies the amplified RF signal to the tuner 34.
The tuner 34 processes the RF signal supplied from the LNA 33 into a transport stream, and outputs the transport stream.
Specifically, the tuner 34 includes an RF processor 51 and a demodulator 52.
The RF processor 51 converts the RF signal supplied from the LNA 33 into an IF (Intermediate Frequency) signal, and supplies the IF signal to the demodulator 52.
The demodulator 52 demodulates the IF signal supplied from the RF processor 51 into a transport stream, and outputs the transport stream.
Since the LNA 33 is connected to the front stage of the tuber 34, the broadcast receiver 11 has a low NF. Therefore, the broadcast receiver 11 has a higher reception sensitivity for broadcast signals transmitted with weak radio waves than broadcast receivers that are free of an LNA.
There has been proposed an LNA having a path for amplifying an input signal and a path for bypassing an input signal, so that an input signal can selectively be amplified and bypassed. See, for example, Japanese Patent Laid-Open No. 2004-274713 (hereinafter referred to as Patent Document 1)